You can change this now in User CP.
The item from ICC10 Marrogar isn't really that great, too much spent on Hit :S
You can defeat Arthas (in a few months time, 2-2.5 months I'm guessing), but I don't think you get to kill him - I'm not 100% sure on this, but I think there was something mentioned about Arthas still being around at Deathwing's emergence so he may still be aroundWait so you can kill Arthas? and if so can you wield frostmourne?
Presumably alts :36 times? What?